1. Field of the Invention
The invention relates to an apparatus for the production of molded concrete parts in a molding machine.
2. Description of the Related Art
Apparatuses for the production of molded concrete parts, such as paving bricks, for example, are typically used for machine production and contain a molding machine having a punch unit and a lower mold part configured as a mold, into which the punch unit can engage. Usually, one mold insert is or a number of mold, inserts are configured in the lower mold part, whose cavities are open toward the top and the bottom. The lower mold part is set onto a horizontal bed with a lower delimitation plane of a brick field, which bed closes off the lower openings of the mold. The mold inserts are filled with concrete mixture through the upper openings; this mixture is subsequently pressed by way of pressure plates disposed on the punch unit, in that the pressure plates are lowered into the mold inserts through the upper openings. Subsequently, solidification of the concrete mixture to form, shape-stable molded concrete parts takes place by means of shaking, typically of the bed. The parts are unmolded through the lower openings of the mold inserts.
The punch unit is connected with a vertical movement unit of the molding machine, which unit is typically hydraulically activated, and can be displaced vertically by means of this unit. The connection can be made, in a conventional design, by way of a top-load unit, which, together with the punch unit, usually forms an upper mold part as a module that can be handled as one part. A uniform brick height is achieved even with different compaction of the concrete mixture, by means of a stop on the punches of the punch unit.
In known molding machines, the connection between the upper mold part and the lower mold part has particular significance. Thus, it is known, for example from DE 36 38 207 A1, that in the case of such molds, there is a risk of collision of the pressure punch with the top side of the lower mold part in the case of insufficient alignment of the upper mold part relative to the lower mold part. This risk particularly occurs when the upper mold part is guided into the lower mold part in the molding machine, in order to form and compact the molded concrete part to be produced. According to solutions known from the state of the art, an attempt was made to circumvent this risk by precisely aligning the upper mold part with the lower mold part, and providing corresponding introduction bevels on the mold inserts, which facilitate introduction of the pressure plates.
The connection between upper mold part and lower mold part, however, was also investigated in greater detail in the state of the art, in a different connection. Thus, a brick molding machine is known from DE 199 24 926 A1, on the guide columns of which machine a brick mold that can be moved up and down is disposed. The brick mold consists of a lower mold part and an upper mold part, which are disposed so that they either can be firmly connected with one another or can be displaced relative to one another, depending on the work cycle. This arrangement allows simple further processing, particularly by means of a pull-off mechanism, which separates lower mold part and upper mold part from one another.
A brick mold for the production of concrete bricks is known from DE 10 2005 048 930 A1; this mold comprises an upper mold part having at least one punch having a pressure piece, and a lower mold part having at least one mold insert, for use in a brick molding machine, wherein the lower mold part can be moved up and down in a brick molding machine. The lower mold part can be laid down onto a mold bed of the brick molding machine, and the upper mold part can be coupled with a machine accommodation of the brick molding machine, which accommodation can be moved up and down. A filling box of the brick molding machine can be moved over the lower mold part, and the upper mold part and/or the lower mold part has play relative to a machine frame of the brick molding machine. In this connection, a centering device is provided for alignment of the lower mold part and of the upper mold part in an xy plane. In this regard, precise centering of the two mold parts relative to one another is brought about, wherein a conical section of the centering device slowly releases centering of the mold parts again after dipping of the pressure piece into the mold insert.